Add flow graph printing into a .cfg file with flag --print-flow-graph-file.

vm/dart.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/dart.h"
 
 #include "vm/dart_api_state.h"
 #include "vm/flags.h"
 #include "vm/freelist.h"
 #include "vm/handles.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/port.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
 #include "vm/thread_pool.h"
 #include "vm/virtual_memory.h"
 #include "vm/zone.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, print_class_table);
 DECLARE_FLAG(bool, trace_isolates);
 
 Isolate* Dart::vm_isolate_ = NULL;
 ThreadPool* Dart::thread_pool_ = NULL;
 DebugInfo* Dart::pprof_symbol_generator_ = NULL;
+FileWriterFunction Dart::flow_graph_writer_ = NULL;
 
 // TODO(turnidge): We should add a corresponding Dart::Cleanup.
 bool Dart::InitOnce(Dart_IsolateCreateCallback create,
                     Dart_IsolateInterruptCallback interrupt) {
   // TODO(iposva): Fix race condition here.
   if (vm_isolate_ != NULL || !Flags::Initialized()) {
     return false;
   }
   OS::InitOnce();
   VirtualMemory::InitOnce();
@@ skipping 71 matching lines @@
 }
 
 
 void Dart::ShutdownIsolate() {
   Isolate* isolate = Isolate::Current();
   isolate->Shutdown();
   delete isolate;
 }
 
 }  // namespace dart